Die drawing of hollow glass blanks



Sept. 28, 1948. c. P. BYRNES DIE DRAWING OF HOLLOW GLASS BLANKS.

Filed Aug. 20, 1945 muy Patented Sept. 28, 1948 DE-.DRAWING OF HQLLQvvdLASSLANKS ClarenceP: emes, Fortfl''au'derlmfla; Application Augusttzfl, 1943,;Serial N: &99,433

, MM invention: relates` to apparatus for drawing sized hollow -glass blanks such as ppe, tublng, cylinders, polygonal shapes, etc., from fore- -hearths or\ doghouses connected to .tenk. furnaces, or'from atankurnaceitself in a sheltere'd" portionthereof; It. isd'esigned to cfeapenand improvethe process and apparat'us as well as to in: creaseaccuracy, quality, andoutput 'of the hollow blanks. V

Heretoforeglasscylind'ers havebeen drawn and sized intermittentl by upward drawing With a belt through two-part dijes, froma double pot mounted'. in a; kiln; the glass is. ladlecl' ntermittentim into such. pot. In using my apparatus the glass is conti'zuously` supplied'. from the: tank to the drawing, station or Stations. and 'a considerable lossofglas-s aswell. as'oss [of time. is avoded dllesslabonusedl Ati the' same time, waiting fon "meliting back"` or preparingg the gl'ass bath between. each: blank drawing is avoidedi In the pz eferredorma succession of hlanksfis draw'n in continous manner i e.with cont'inuous 'connection to the glass bath. In case of crash or other aceident,othe bath. connection: may. be' sev'- ered-and melting. back-.carried out. I'f'then remelted in place, provision is made for hasten'ing theremelt, or the colder glass may bemovdf out into the furnaceproper for remelt'; or. drawing started' at another drawing station* until remelti'ng isaccompllshed.

In the drawings, Figure 1 is a; dagrammatb 'vertical' section showinga; dog'house" tank' fur'- ace withoa preferred, form' of dra'wing system; and

Eigure 2"is avdiagrammatic plan View of theiend portionof'a, tankfurnace and forsehearths.

In the prefrred form of apparatus of Figure `1; a forehearth' 2`, extending' out from' the ta'n'k f'rnace 3, has a' topstone 4 with a' circul'ar'hole containing a cylindrical refractory'sheld !i surroun'dingfa fluidcooled metalli'cshie'ld 5a`. These shielcls are adjusted vertically by'eyes 6, 611, and may. consl'st of a hollow 'metallic centre with fluid cooling connections and a. refra'ctory surrounding jacket. This'shie'ld" device c'oactswith one of a. series of' partlysubmerged fi oating refi'actory'rin'gs 'I to' cut'off the Heat currents above the bath from t'h'e drawing place. The shild preferabfy interi-its with'` a'cir'cular recess of the flating ring' as shown', to hola the ring in' cormeet concentrc' position below the drawing' open'- hg`and" around" the air nozzle and sizing'die's.

8 i's' a' die rng'of 'heat-resistant alloy made in multiple are-shaped 'partsand" hollw for" fluid cooling; which is supported" at" a leve1^"withih' a alibi' or material i s" 4 2 zone far' enough above the level of. the glass bath to: prevent it forming an opaque skin or even marrlng; of the glass; and yet near. enoug'hto bend the. glassin and size and shape. it to cylihdrlcal or, polygonal form while. still p1astc..'1`he interior surface of the. ring 8' corres-ponds to the shape desiredff'or the walls of the hol-low. blank. Thi distance will depend onthe percentag. .of cooling in shields 5, Sa; the height of' the top' stone above the bath, etc., but is generally over 6 or 8 inch'esfrom the bath. surface. An exterior transparent skinforms on the cylnder' B- fore it' strikes the curved deflecting. and s'lzn'g surfacesof'the die; but no cpaqueskn is 'fr'med by the die when at the proper' level;

In this form the disten'sion' air isas'uppd through valVed, air supply pipe 9 leading i to vertical cylinder nozzl'e oextendi'ng', up'wardlyto a. level above the glas's bath and" substantially com''e'ntrie with the, shaping dies above and with the cyli'ndrical shi'eId" 5. This nozzle is either made 'ofrefractory material', or'of a metal alloy o'thgh heart" resistanee. or a earbid'e, or* fised quartzaor silic'a,. or both.. It' may be' ofrefractory material surrounding and protecting a', metal a'l'- loy tube; or it may be of refractory line& with `h'fl temperature ins'lation' cement, Grof an ajllby tube with such' a' cement between' tIan'd the refractory," ca'sing; If of a heat-resistant metal alloy such als' the' rhodiu'm'alloysnow used in cutlets' for molten glass, the nozzlewill'be proteetedhy freezing of molten glass aroundit; this frozen annulus separating it from the molte'n bath.. Thisnozzle Supplies` controlled distendiig air;. ,anda1so acts:as guideand protection forthe sten" lli of' a horizontal' stopper l'2` which' holds the' -desired ar'pressureln the' glass'cylinder being drawn. This stopper' l'2'is' removablycdnnectd to the upp'er end' ofguide tube or stem H, which stem' preferably* has 'centering prongs or projections lZa' enga'ging" the innersurf ace of the uzzle. The stoppe'r may preferably bevertieally ad'j usted by moving its stem ll vertically', 'as m ii'cated' lay the d'ouble head'ed" arrow at the' lower parti of-Figure l; The stopper of heat-resstant changed' for diferent sizes and cross=sectiona1 shapes of" hollow blanks anti fits' closely the' ihn'er surface' of the sze'd" ll'ank witha gap of, say, %g of an inch or less, which a'cts as a desira'be-vent for the air pressure withpherc: The' air holding stopper l`2 is ositi'one'd vertical' within' the szed' die-drawn' portion' of the" blankbehg di'awn, after it has been acted upon by the'dl'es; being either within' or alov'e the level of the shapir and sizing dies. This is important since in the lower parts of the glass blank below the die level the blank is egg-shaped or elliptical with varying axes, and is not truly circular in cross-section; hence if the stopper were below the die, th escaping air would vary largely and hence vary the cylinder size undesirably. There is an important coaction between the die and stopper in holding the air pressure relatively constant, by keeping the air-escape an or vent relatively constant.

During operation the air fed up through the nozzle cools the stopper stem and the nozzle and maintains the needed low superatmospheric pressure in the plastic rising glass blank, this air having the usual controls as to Volume. pressure, etc. 4 i

After the original draw has reached a desirable height, continuous draw apparatus of any desirable type may be put into operation, either by endless belt grippers engaging the glass cylinder itself above the die level as indicated by dotted lines is; or by the deforming lifter system'of my Patent No. 1,425,746 'of 'August 15, 1922, or by any other desirable system. If the cylinder is deformed for lifter engagement, as shown for example in my said patent, this deforming should be done below the die level, the lifters engagingthe deformed portions above the level of the dies.`

Blanks of the desired lengths may be severed from the rising cylinder during draw, by electric crack-'cit sticks such as disclosed in my said patent. The heating wire of such stick is applied at a level above the stopper and allowed' .to travel up with the cylindrical blank as it rises and then opened and withdrawn and a cold iron applied to crack and sever the glass. The wire loop is then moved down for the next severance.

As an example of relative sizes, in drawing a cylinder of, say, 8 inch or slightly greater diameter, the refractory air nozzle maybe about 3 to 4 inches diameter, the supporting stem (pipe or rod) about 1 inch diameter, and the refractory fioating rings of about 18 to 20 inches inside diameter.

'In case `of a cylinder crashing or a breakdown from 'any cause, so that chilled glass is present in the drawing ring 1, several different courses may be followed during the interim.

Thus, the stopper !2 may be removed and its stern or tube dropped down; the cylindrical shield or shields 5, 5a, may be lifted and a heating device lowered into thedraw-hole in the topstone. .One form of such a gas burning reheater is known in the trade as a "selas Burner". which would effectivelyl and rapidly reheat the glass within the ring by radiation.

Another course is to remove the shields, move the fi-oating ring slightly sidewise, and then lift one side thereof over the. nozzle and shove the ring back into the furnace; and by reversing the movements bring another floating ring from the furnace, and install it around the air nozzle and restore the shields, etc. During this operation, a refractory cover may be applied over the drawhole, and heat current allowed to circulate below it to reheat and keep hot the glass in the doghouse. v

In case of starting to draw another size .or type of blank, the stopper 12 and stem are dis- :connected and another stopper applied of 'suitable size andshape for the desiredblank being drawn. Instead of using movable fioating rings in the bath which are moved in and out of drawing position, the furnace aa may be provided with several forehearths or drawing enclosures za, as shown in Figure 2, and in case of a stoppage or breakdown, the cylindrical shield may be lifted out and a draw made at another forehearth or enclosure while melting back of the refuse glass proceeds at the former forehearth. In such case the drawing apparatus may be moved from forehearth to forehearth.

The cylinder may at a level above the die pass up within a heat retaining enclosure which acts to anneal the rising cylinder and prevent air drafts thereon which might crack the glass. This enclosure may be of two or more parts split vertically and adjustable toward and from the glass axis; or may be partial, as desired. It may be of refractory, metal, reinforced refractory or metal.

Air may be supplied through a tubular stem of the disc, this air emerging through holes below the disc, the stem fitting within the nozzle to prevent escape of air beyond that desirable for venting.

The advantages of my invention result mainly from continuous operation with sizing dies, i. e., continuous connection of a hollow blank with the glass bath and intermittent severing of sized blanks of the desired lengths. This gives a large increase in production, while the dies cooperate with the stopper which keeps a superatmospheric pressure within the rising hollow glass tube. That is, the dies shape and size the glass to final size and form and thus enable a stopper'to fit the shaped and sized bore suificiently to hold the desired pressure and at the same time allow desirable venting which prevents "breathing" ot the glass in the plastic zone of the blank. If the glass were not shaped and sized, the loss of air would be variable and would cause large varia-` tions of size of blank due to variations in the distending pressure. The ring-shaped enclosure for the draw (floating ring) also aids in this substantial uniformity, as does also the cylindrical shield which keeps out the surrounding heat currents over the bath during the draw. All these elements are substantially concentric with the blank. v

The stopper' which keeps air pressure within the plastic zone of the rising hollow blank may be of compressed asbestos or other heat-resistant material. It may be carried on a tube or rod which in turn is supported within and by the heat-resistant air supply nozzle; and it and the support may be lifted upwardly for removal and replacing in case of a temporary shut-down or a change in the glass blanks to be' made. The cylindrical shield device which protects the draw may be made as one element-a refractory shield with an inner water-cooled core. Instead of outwardly projecting forehearths, the shelt-ered drawing bays may be cut into and form parts of the ,tank furnace proper. suitable means are used for adjusting the 'stopper and stern, for control and regulating the air supply, for removal of cylindrical blanks, etc. Floating rings of different sizes and shapes may be used for drawing of cylinders or tubes of different sizes, the sizing dies being correspondingly changed.

Many other changes may be made within the scope of my claims, since I consider myself the first to devise a continuous die drawing system for hollow glass blanks where continuous connection is kept between the rising blanks and the glass bath in drawing a series of blanks; especially where some superatmospheric pressure is naintained in the plastic zone of the rislng glass meniscus, even during severing and removal of blanks.

I claim:

l. In apparatus f-or forming hollow glass blanks, a receptacle for a molten glass bath, means for drawing hollow glass upwardly from a glass bath therein, a relatively stationary shaping and sizing die having an interi-or surface corresponding to the desired external shape of the hollow glass blanks and through which the hollow glass is drawn, said die being arranged to defiect the plastic walls of the hollow glass inwardly as lt is drawn upwardly, an internal stopper supported at a level at least as high as that of the external die and arranged to coact with the inner surface of the shaped and sized hollow glass to hold distention air pressure therein below the stopper level, and means for continuously supplying distention air at a level below the stopper.

2. In apparatus for forming hollow glass blanks, a receptacle for a molten glass bath, means for drawing hollow glass upwardly from a glass bath therein, a relatively stationary shaping and sizing die having an interior surface corresponding to the desired external shape of the hollow glass blanks and through which thehollow glass is drawn, said die being arranged to deflect the plastic walls of the hollow glass inwardly as it is drawn upwardly, an internal stopper supported at a level within the rising hollow glass at least as high as that of the external die and having an external contour corresponding to and a circumference slightly smaller than the shaped and sized hollow glass drawn up around it.

3. In apparatus for drawing hollow glass blanks, a container for a molten glass bath, means for supplying heat, means for drawing hollow glass upwardly from the glass bath, an enclosure within the container arranged to at least partially shield the hollow glass from surrounding heat, said enclosure corresponding in general internal contour to that of the hollow glass drawn up, a shaping and sizing die arranged to defiect the rising hollow glass inwardly while still plastic, said die being sufficiently far above the bath level to prevent opaque skin ormation, an internal stopper above the level at which the die deflects the rising walls of the hollow glass inwardly, said stopper having an external contour corresponding to the internal cont-our of the shaped and sized hollow glass, and means for continuously supplying distention air below the stopper.

4. In apparatus for drawing hollow glass blanks, a container for a molten glass bath, means for supplying heat, means for drawing hollow glass upwardly from the glass bath, an enclosure within the container arranged to at least partially shield the hollow glass from surrounding heat, said enclosure corresponding in general internal contour to that of the hollow glass drawn up, a shaping and sizing die arranged to defiect the rising hollow glass inwardly while still plastic, said die being sufliciently far above the bath level to prevent opaque skin formation, an internal stopper above the level at which the die deflects the rising walls of the hollow glass inwardly, said stopper having an external contour corresponding to the internal contour of the shaped and sized hollow glass, an annular heat shield coacting with the enclosure to give an enclosed atmosphere for the draw, and means !or continuously supplying distention :air below the stopper.

5. In apparatus for forming hollow glass blanks, a receptacle for a molten glass bath. means for drawing hollow glass upwardly therefrom, a relatively stationary stopper around which the hollow glass is drawn, means for supplying distention air below the stopper, and an external relatively stationary die through which the hollow glass is drawn, said die being arranged to deflect the rislng glass inwardly to size and shape successive portions thereof to correspond to the external contcur of the stopper before the hollow glass reaches the stopper level; whereby substantially uniform pressure is maintained in the rising hollow glass below the stopper.

6. In apparatus for fo-rming hollow glass blanks, a receptacle for a molten glass bath, means for drawing hollow glass upwardly therefrom, a relatively stationary stopper around which the hollow glass is drawn, means -or supplying distention air below the stopper, and an external relatively stationary die through which the hollow glass is drawn, said die being located at a level as low as the stopper and being arranged to deflect the rising glass inwardly to size and shape successive portions thereof to correspend to the external contour of the stopper before the hollow glass reaches the stopper level; whereby substantially uniform pressure is maintained in the rising hollow glass below the stopper.

CLARENCE P. BYRNES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 702,015 Lubbers June 10, 1902 84:6,102 Frink Mar. 5, 1907 1,425,746 Byrnes Aug. 15, 1922 1,892,806 Pedersen Jan. 3, 1933 1,987,633 Pedersen Jan. 15, 1935 2,166,871 Luertzing L July 18, 1939 2,267,554 Despret Dec. 23, 1941 

